Earth inductor compass



y 2, 1940- P. F. BECHBERGER 2,205,018

EARTH INDUCTOR COMPASS Filed Dec. 29, 1958 P. F? Beollberg'er.

Bend. mil. a corp ration or Application memb :9. ins. Serial no.

One or the objects of the invention is to pro-.

. vide a novel earth inductor compass system which indicates compass direction throughout three hundred sixty degrees (360") without a follow-up motor or other additional and complicated mech-.

Another object is to provide an earth inductor compass system comprising a novel remote compass indicator in combination with a novel earth inductor.

A further object of the invention is to providea novel earth inductor compass system comprising means including a highly permeable magnetic member having a plurality of pole pieces and 0 provided with a plurality of windings or coils thereon for generating a plurality of alternating current E. M. F.'s from the earth's magnetic field,

the amplitudes of said E. M. F.'s being respectively proportional to the cosine of the angle between the magnetic center line of each winding or 2 coil and the direction of the earth's magnetic field, means for generating a single-phase E. M. F. having the same frequency and substantially the same phase as the E. M. F.'s generated from the earth's magnetic field, and means comprising a rotor member and a stator member, one

of said members having a plurality of windings connected in polyphas'e relation and respectively energized by the plurality of E. M. F.'s generated from the earth's magnetic field, and the other of said members having a single-phase winding energized by the single-phase E. M. F. whereby,

upon angular displacement of said permeable magnetic member with respect to .the earth's field,

, the rotor member of said last-named means is 40 correspondingly displaced by the reaction between the resultant field produced by the plurality of E. M. F.s of the polyphase-connected windings and the field of the single-phase winding of the indicating means to assume an angular po- 5 sition corresponding to the direction of the earth's magnetic field.

A still further object of the invention is to provide a novel earth inductor compass system comprising means including a highly permeable magnetic member pole pieces equally spaced angularly and each provided with a winding or coil thereon for generating three alternating current E. M. F.'s from the earth's magnetic field, the amplitudes of said E. M. F.s being respectively proportional to the cosine of the angle between the magnetic center line of each coil or winding and the direction of the earth's magnetic field, means for generating a local single phase E. M. F. simultaneously 0 with the E. M. F.'s generated from the earth's the resultant km iota-cm field and the. samefrequencystantially the samephaseasthe-latter 8.1!. l". means for amplifying the. three I. ll. -l".'s generated from earth's field, and indicating means connected to said amplifying means and to said 5 single-phase E. 1L1". 'generating,,.-means, said indicating means comprising a stator having three windings connected in three-phase relation and respectively energized by the three 'amplifled E. M. F.'s generated from the earth's field," and a. rotor having a single-phase winding en'- ergized by the single-phase E. M. 1''. whereby, upon angular displacement of said permeable magnetic member. with respect to the earth's field, the rotor of said indicating means 'is correspondingly displaced by the reactionbetween field produced by the three E.- M. F.'s of the three-phase-connected stator windings and the field of the single-phase winding to indicate the direction of the earth's masnetic field. The above and other objects and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together, with the accom- 25 panying drawing wherein one embodiment of the invention is illustrated. It is to be expressly understood, however, thatthe drawing is for the purposes of illustration and description only, and

is not to be construed as defining the limits of the invention, reference being had for this purpose to the appended claims.

The invention consists substantially in theconstruction, combination, location and relative arrangement of parts and circuits forobtaining the 85 results desired in accordance with the foregoing objects, as will be more fully hereinafter set forth in the specification, as shown in the drawing by way of example, and as finally pointed out in the claims.

The single figure of the drawing is a schematic circuit diagram of one exemplary arrangement embodying the present invention.

It is well known that the amplitude of an E. M. F. induced in a coil by a magnetic field is 45 proportional, to the cosine of the angle between the magnetic center line of the coil and the direction of the magnetic field. Therefore, if an E. M. F. be induced in a coil by the earth's magnetic field, the amplitude of that E. M. F. will be 50 proportional to the cosine of the angle between the magnetic center line of the coil and the direction of the earths field.

The present invention is based upon the abovestated principle and a plurality of coils, in the 5 present instance three coils connected together in three-phase relation, are provided which are wound on a relatively stationary highly permeable magnetic member having three radially extending pole pieces spaced angularly apart, there being a coil on each pole piece. This magnetic member may be fixed to the craft on which the direction of the earth's field is to .=be'indicated, with the pole pieces lying in a substantially horizontal plane so as not to be affected by the vertical component of the earth's field.

An alternating current E. M. F. is induced in each of the three coilsby the earth's magnetic field by periodically varying the earths magnetic fiux in the pole pieces of the permeable member in a manner to be described more fully hereinafter, the amplitudes of said E. M. F.s being respectively proportional to the cosine of the angle between the magnetic center line of each coil and the direction of the earth's field. A local single-phase alternating current E. M. F. is also generated having the same frequency and substantially the same phase as the three E; M. F.s.. The three E. M. F.s generated from the earth's magnetic field may then be separately amplified, if desired, by any suitable amplifiers such, for example, as thermionic vacuum tube amplifiers, and are supplied to an indicator. The locally generated single-phase E. M. F. is likewise supplied to the indicator which includes a stator member and a rotormember, one 01 said members having three windings connected in three-phase relation and respectively energized by the three E. M. F.s generated from the earth's magnetic field, and the other 01' said members having a single-phase winding energized by the locally generated single-phase E. M. F. In this manner, when the permeable magnetic member is displaced angularly in azimuth. as when the craft on which the device is mounted makes a turn in azimuth, the three voltages induced in the three coils are amplified and reproduced in the three-phase-connected windings of the indicator and produce a resultant field which reacts with the field produced by the locally generated E. M. F. in the single-phase winding of the indicator, thereby angularly displacing the rotor of the indicator an amount corresponding to the angular displacement of the permeable magnetic member, a pointer being connected to the rotor to indicate the angular thereof and, hence, the direction of the earths field.

Referring now to the single figure of the drawing, the earth inductor device is shown at I and comprises a highly permeable magnetic member constitutecLin the present embodiment, by three radially extending pole pieces 2, 3 and 4, angularly equally spaced one hundred twenty degrees apart. The inductor device I is relatively stationary and may be fixed to the craft (not shown) on which the direction of the earth's field is to be indicated, with the pole pieces arranged in a substantially horizontal plane. Wound on the pole pieces 2, 3 and 4 are coils or windings 5, 6 and 1, respectively.

Means are now provided for generating alternating current E. M. F.'s in the coils 5, 6 and 7 respectively, by the earths magnetic field by periodically varying the earths magnetic .fiux in the pole pieces 2, 3 and 4 and, in the form shown, said means comprise a rotor 8 also of highly permeable magnetic material such aspermalloy, for example, provided with radial projections or pole pieces 9, l0 and II which form air gaps, l2, l3 and I 4 with the cooperating inner ends of the pole pieces, 2, 3 and 4, respectively. The rotor member 8 is drivably connected to a suitable driving device such, for example, as an electric motor M for rotation by the latte as indicated and 1, respectively. The

.is shown at 0..

--in three-phase relation displacement by the dotted line lia representing a drive shaft. Upon rotation of the rotor 8 the reluctance oi the magnetic paths formed by the-gaps l2, l3 and I4 is increased and decreased periodically and thus the flux produced in the pole pieces, 2, 3 and 4 'by the horizontal component of the earth's field is periodically varied, thereby inducing alternating E. M. F.'s in the coils 5, i amplitudes o1 these E. M. F.sare respectively proportional to the cosine of the angle between. the magnetic. center line of each coil and the direction of the earth's field. The angle between the magnetic center line of coil 5 on pole piece 2 and magnetic North 5, 6 and 'l are connected at the junction point It.

If desired, means may be provided for separately amplifying the E. M. F.'s generated in The coils or windings an indicator is provided which is shown at H and which comprises, as shown. an inductive device of the so-calied Selsyn'or Autosyn type, including a stator having three windings ll, l9 and 20 connected in three-phase relation at the junction 2|, and a rotor having a single-phase winding 22 and an indicating pointer II.

The three amplified E. M. F.'s generated by the earth's magnetic field are supplied respectively to the individual three-phase-connected windings l8, l9 and 20 and for this purpose said windings are connected field.

Any suitable generator G may be used for generating the single-phase alternating current for ment is of the type described and claimed in the co-pending application of A. A. Serial No. 248,344, filed Dec. 29, 1938.

As shown, said generator (3 comprises a variable electrostatic condenser having a stationary plate provided with radially extending portions 23, 24 and 25, and a rotatable plate pro- The variable condenser is connected to the input of a thermionic vacuum tube VT through a fixed condenser C1 and across a resistor R1, and 7B se ame "=43 the output of the vacuumtube VT; is connected is ly displaced by the reaction beto the single-phase winding 22 through a transtween the 'resuitantileld'pro uo b! th pillformer 1'4. v rality of E. M, it's of the polyph f A D. C. charging potential is on the winding! and the-held of the single-phase wind 5 variable condenser through a resistor R1, andthe ing of the indicating meansto assume an angular a potential across said resistor Ra is periodically position corresponding to the direction of the increased and decreased by rotation of the rotatearth's magnetic field. able portions it. 21 and of the condenser G 2. An earth inductor compass comprising, in 'by the electric motor M. This vary nl potential combination, means includinga highly 10 is am lified by the vacuum tube W4, thereby magnetic member having threcradially extendin producing a single-phase alternating current in ing pole pieces equally spaced angularly and each the output of the transformer T4. which current provided with a winding thereon for g is supplied to the single-phase rotor winding y of the remote indicator H by leads it and 3|. netic field, the amplitudes of said E. M. I): be-

lo the frequency of saidcurrent depending upon in: respectively proportional to the cosine of the llthe speed of rotation of the rotatable portions angle between the" magnetic center line of each of the condenser G and being the same as the winding and the direction of the earth's field, frequency of the alternating currents induced in means for locally generating a single-phase alterwindings 5,] and I because the same motor 11- nating E. M. F. simultaneously with the three so rotateselement 8 as well as condenser G. The E. M. 1".s generated from the earth's field and I 40 aircraft.

phase of these currents is likewise substantially having the same frequency and substantially the the same. same phase as the latter E. M. 1".s, means for The resultant field produced by the amplified amplifying the three E. M. R's generated from E. M. F.s in the three-phase-connected windthe earth's field, and indicating. means connectas ings II, II and "is such that the reaction thereed to said amplifying means and said singleas of with the field of the single-phase rotor windphase E. M. F. generating means, said indicating ing 12 causes the latter to align itself accordmeans comprising a stator having three windmined by the windings I. 6 and I of the earth inand respectively energized by the three E. M. 1".s

$0 ductor l, and this direction is indicated by the generated from the earths field in the first- U pointer 3| which is attached to the rotor 22. named windings, and a rotor having a single-v There is thus provided a novel earthinductor hase winding thereon energized by the locally compass comprising a novel earth indicator and generated single phase E. M. F. whereby, upon a novel indicator, whereby the compass direcangular displacement of said permeable magtion can be indicated throughout three hundred netic member with respect to the earth's field, I sixty degrees (360) and without a follow-up the rotor of said indicating means is correspondmotor or other additional and complicated mechingly displaced by the reaction between the reani ms. th r y pr v din a r ativ y l htsuitant field produced by the three E. M. E's of weight compass particularly adapted for use on the three-phase-connected stator windings and the field of the single-phase winding to indicate 40 while'only one embodiment of the invention the direction of the earth's magnetic field.

has been illustrated and described, various 3. An earth inductor compass comprising, in changes in f rm. construction and relative rcombination, means including a permeable magrans m n of Pa wh w l now appear to netic member having a plurality of pole pieces 46 those skilled in the art, may be made without deequally spaced angularly and provided with a p r n from t op of the vention. R ferplurality of windings thereon for generating a enceisthereforetobehad tothe appended claim plurality of alternating E. M. Efs from the for a definition of the limits of the invention. earth's magnetic field, the amplitudes of said What is claimed is: E. M. F.s being respectively proportional to the 50 1. An earth inductor compass compri ing. in cosine of the angle between the magnetic center 50 combination, means including a Permeable line of each winding and the direction of the magnetic m m h ving a plurality of pole earth's field, means for locally generating a pieces and provided wi h a p ur i y of w ndings single-phase alternating E. M. F. simultaneously thereon for generating a plurality of alternating with the E. M. F.s generated from the earth's E. M. F.'s from the horizontal component of the field and having the same frequency and sub- 55 earths magnetic field, the amplitudes of said stantialiy the same phase as the latter E. M. R's,

E. M. F-'s being p ive y proportional to the means for amplifying the plurality of E. M. F.s

cosine of the angle between the magnetic center generated from the earth's field in the firstline of each winding and the direction of the named windings, and indicating means connectearths field, means for locally generating a sined to said amplifying means and said single- 6 gle-phase alternating E. M. F. simultaneously phase E. M. F. generating means, said indicat with the E. M. F.'s generated from the earths ing means comprising a. stator having three field and having the same frequency and subwindings thereon connected in three-phase restantially the same phase as the latter E. M. F.s. lation and respectively energized by the three and means comprising a rotor member and a E. M. F.s generated from the earths field in the 65 stator member, one of said members having a first-named windings, and a rotor having a plurality of windings, connected in poiyphase resingle-phase winding thereon. inductively posilations and respectively energized by the E. M. Fls tioned with respect to said three windings, said generated from the earths field in the firstsingle-phase winding being energized by the lonamed windings and the other of said members cally generated single-phase E. M. F. whereby, 70 having a single-phase winding energized by the upon angular displacement of said permeable locally generated single-phase E. M. F. wheremagnetic member with respect to the earth's by, upon angular displacement of said permeable field, the rotor of said indicating means is cormagnetic member with respect to the earth's respondingly displaced by the reaction between field, the rotor member of said last-named means the resultant field produced by the three 75 ing the flux due to the horizontal component or direction of the earths magnetic field, means for locally generating a single-phase alternating E. M. F. simultaneously with the E. M. F;s generated from the earth's field and having the same frequency and substantially the same phase as her of said last-named means is correspondingly displaced by the reaction between the resultant field produced by the plurality of E. M. F.s of the polyphase-connected windings, and the field of the single-phase winding of the indicating means to assume an angular position corresponding to the direction of the earths magnetic field.

5. An earth inductor compass comprising, in

means including a highly permestator member having three radithe direction of the earth's magnetic field, means simultaneously driven by the rotor driving means for locally-generating a single-phase alternating E. M. F. simultaneously with the three E. M. F.'s generated from the earth's field and having the same frequency and substantially the same phase said single-phase E. M. F. generating means, said indicating means comprising a stator having three windings thereon connected in a threein the first-named windings, and a rotor having a single-phase winding thereon energized by the locally generated ainglephase E. M. F. whereby, R

upon angular displacement magnetic member with respect to the earth's the resultant field produced by the three E. M. F.s of the three-phase-connected stator windings and the field of the single-phase winding to indicate the direction of the earth's magnetic 6. An earth inductor compass comprising, in mbination, means including a relatively stationary permeable magnetic member having a plurality ity of E. M. F.s of the polyphase-connected windingsand the field of the single-phase winding 01' earth's magnetic field.

7. An earth inductor compass comprising, in combination, means including a permeable mag- PAUL FRANKLIN BECHBERGER. 

